The most common and most likely answer to this crossword clue is the 4 plus 5 letter word GLAD HANDS
I've seen this crossword clue in Financial Times
G
L
A
D
H
A
N
D
S
Buddy explains!

The straight part
We know that "Warmly welcomes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case warmly welcomes = glad hands.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
Crossword Answer definitions
GLAD HANDS verb- To be overly friendly with (a stranger) in order to gain an advantage.
- To extend a glad hand (to someone); to welcome warmly.